The overall objective of this project is to develop gutless adenovirus vectors for use in experimental animals, to determine the best protocol for prolonged expression following delivery in vivo, and to use these vectors to express low density lipoprotein receptor (LDLR) and very low density lipoprotein receptor (VLDLR) in animal models of familial hypercholesterolemia (FH). The specific aims are (i) We will examine the effect of long-term expression of VLDLR and LDLR in transgenic mice with an LDLR -/- background using an inducible binary transactivation system. This system was developed by investigators in Project 3. Different levels of expression of the transgene can be accomplished by graded subphysiological doses of an exogenous compound RU486. (ii) We will develop gutless adenovirus vectors expressing reporter genes (e.g. alpha1- antitrypsin), VLDLR and LDLR which will be tested in mice and rhesus monkeys. (iii) We will develop a protocol for the repeated administration of gutless vectors to mice and rhesus monkeys. Transient immunosuppression protocols and vectors of different serotypes will be tested. (iv) We will test and compare the gutless vectors expressing mouse LDLR and VLDLR in LDLR -/- mice for their efficacy in reversing the hypercholesterolemia and their general health effects, and the extent of aortic atherosclerosis. (v) We will examine the effect of hepatic transfer of the rhesus LDLR and VLDLR genes in heterozygous and possibly homozygous LDLR-deficient rhesus monkeys. This project interacts closely with Project 2 for the gutless vector development, and Project 3 for the regulated expression system. It will be supported by the scientific Cores A (Primate Core), B (Vector Production Core) and C (Pathology Core).